The present invention relates to a metal gasket with a seal ring for use as a cylinder head gasket of an internal combustion engine.
In an engine with a cylinder liner, the cylinder liner is installed inside a bore of a cylinder block. In this case, an upper end of the cylinder liner is provided with a flange, and the cylinder block has an annular recess, wherein the flange is placed in the annular recess of the cylinder block. It is designed that the upper end of the cylinder liner is flush with the upper surface of the cylinder block, but the upper end of the cylinder liner may be located slightly lower than the upper surface of the cylinder block.
A gasket for the engine with the cylinder liner is disposed under the cylinder head and above the upper surface of the cylinder block and the upper end of the cylinder liner. If the upper end of the cylinder liner is lower than the upper surface of the cylinder block, a small space is formed between the cylinder head and the upper end of the cylinder liner. In this case, conventionally, the gasket has a fire ring around the cylinder bore to securely seal therearound, which makes the gasket inevitably thick.
In case a thick gasket, such as a gasket with a fire ring, is not suitable for an engine, a gasket may be formed of one metal plate, such as Japanese Utility Model Publication No. 61-14748. In this gasket, the metal plate includes a bead and a sealing portion in a ring shape around the cylinder bore. The sealing portion is made thick with a thickness of 0.03-0.05 mm by plating, so that the sealing portion operates as a fire ring.
Since the sealing portion made of plating is expensive and needs extra labor, the above gasket with the sealing portion is not appropriate. Therefore, a thin annular ring has been fixed by welding on a metal plate around a cylinder bore instead of forming the sealing portion by plating. When the gasket with the thin annular ring is installed between the cylinder head and the cylinder block and is tightened, the thin annular ring regulates a compressible height of a bead formed around the thin annular ring, and seals a space in case the upper end of the cylinder liner is located slightly lower than the upper surface of the cylinder block.
However, when the above space is shallow or the surface pressure regulation height for the bead formed therearound is low, the thickness of the annular ring must be thin. In this case, it is difficult to prepare and fix the thin annular ring to the metal plate. Also, the processing cost becomes high.
Further, in case the cylinder block is formed of light metal or alloy thereof in order to provide a light engine, since the rigidity of the cylinder block is lowered especially around the cylinder bore, if a high pressure is formed around the cylinder bore, the cylinder block may deform around the cylinder bore.
In U.S. Pat. No. 4,711,456, rings connected to each other are disposed in the cylinder bores, but the rings are covered by a cover member. Also, in U.S. Pat. No. 4,754,982, a rubber ring is disposed around a fluid hole, not for a cylinder bore. These rings are not easily assembled with a main part of the gasket.
Accordingly, one object of the invention is to provide a metal gasket with a seal ring, wherein the seal ring can be easily assembled with a metal plate.
Another object of the invention is to provide a metal gasket with a seal ring as stated above, which is suitable to be installed in a narrow space or gap, such as between an upper end of a cylinder liner and an upper surface of a cylinder block.
A further object of the invention is to provide a metal gasket with a seal ring as stated above, which can prevent deformation of a cylinder block in case rigidity of the cylinder block is not so strong.
A still further object of the invention is to provide a metal gasket with a seal ring as stated above, which can easily and slightly regulate a surface pressure of a bead.
Further objects and advantages of the invention will be apparent from the following description of the invention.